Mitochondrial instability in a strain ofSaccharomyces cerevisiae

Abstract

A haploid strain of Saccharomyces cerevisiae has been described which, on glucose medium, segregates vegetatively a high frequency of mutants with different degrees of respiratory impairment. The range of mutants seemingly encompasses both non-revertible ρ- petites and revertible point mutations resembling leaky mit- mutations. The segregants have aberrant cytochrome contents and reduced growth capabilities on fermentable sugars other than glucose; these defects apparently correlate with the degree of respiratory impairment. Genetic analysis of this mutator phenomenon has implicated a nuclear gene which appears to show specificity of interaction with the mitochondrial genome as well as a requirement for glucose repression. The mutator effect seems to extend also to the loci in mitochondrial DNA for resistance to the antibiotics erythromycin and oligomycin.